The carrier is very solid and can certainly withstand this. Whether the same applies to your plastic spoiler is a completely different question... This is the main problem with this carrier and the fact that the lights and licence plate are no longer legible (buses!). It's not for nothing that the vehicle in the product picture has low-lying rear lights and the KS in the bumper. I solved both problems by mounting the carrier higher (not on the bumper) and attaching the upper straps to a roof rack.